地幔中水的赋存状态的研究进展

地幔水不仅对地球物理场的性质有重要影响，而且对地球化学动力学，地幔横向不均一性、地幔对流、低速层、板块俯冲、相平衡、熔融行为、深部地质灾害以及成矿作用等都具有重要意义，因此，地幔水的研究早已引起人们的重视。为了探讨水在地幔过程中的作用，必须搞清楚水的赋存状态。研究表明，地幔中水的储存形式主要有三种：以ＯＨ形式储存的矿物中，以自由相形式存在以及溶解在熔体中，本文对地幔中水的赋存状态研究进展作了综述，     

地幔交代作用：研究进展、问题及对策

有关地幔交代作用的研究始于７０年代早期。近２０年来研究工作的贡献是使人们对与地幔演化和不均一性有关的地幔交代作用特征和交代作用机制有了更多的了解。地幔交代作用很复杂，它取决于交代作用发生的时间、构造环境、交代介质的种类以及与不同深度地幔内各种地质事件有关的流体的组成。进一步深入开展有关交代作用成因、机制及其与各种地质事件关系的研究，对于深入认识岩石圈地幔的演化和不均一特征具有十分重要的意义。对不同构造环境中的不同包体类型进行深入研究，为地幔交代作用提供广泛约束。将传统的地质学、岩石学的研究与地球化学、地球物理学以及现代测试技术相结合，很可能为解决交代作用成因、机制及交代作用与岩浆作用之间的时间先后问题，交代作用与地质事件的关系问题提供有效的方法和途径。     

地幔交代作用与地幔流体

简要综述了地幔交代作用的特征、研究现状及研究热点，阐明了地幔流体在地幔中的宏观、微观分布及其交代作用机理。地幔交代作用及地幔流体的研究，将促进我们进一步认识岩石圈地幔的演化及不均一特征。     

氖指示物标定澳大利亚地幔柱

对利用氖同位素体系标定地幔柱的新方法进行评述,介绍Ｍａｔｓｕｍｏｔｏｔ等在澳大利亚用磷灰石中地幔派生矿物的流体包裹体氖同位素组成研究地幔柱的方法原理及成果,并指责该方法的不足之处。这对于促进有关地幔柱的地球化学示踪剂的研究很有指导意义。     

岚皋金云角闪辉石岩类捕虏体特征

陕西岚皋地区碱质基性超基性潜火山杂岩中的金云角闪辉石岩类捕虏体，主要由透辉石、富钛韭闪石、高Ｔｉ金云母、磷灰石及钛铁矿组成。捕虏体发育三联晶、碎裂边、扭折变形等固相线下变形变质结构，与正常地幔尖晶石二辉橄榄岩成分相比，捕虏体富ＴｉＯ２、Ｆｅ２Ｏ３、ＣａＯ、Ｎａ２Ｏ、Ｋ２Ｏ，贫ＭｇＯ；其稀土元素具富集特征，尤其富集ＬＲＥＥ；微量元素配分型式显示富亲石不相容元素的特征。岩相学、矿物学及岩石化学特征表明，该类捕虏体为交代地幔捕虏体，它代表了北大巴山早古生代裂谷作用时期的异常地幔。交代营力可能源于地幔热柱的上升，在地幔深处可能以熔体交代作用为主，往上逐渐以流体交代作用为主     

峨眉山玄武岩地幔源成分及其变化的微量元素标志

根据峨眉山玄武岩系岩石的稀土元素、不相容元素特征，估计了产生其母岩浆的地幔源成分。讨论了地幔平衡部分熔融和岩浆分离结晶过程中强不相容元素与一般不相容元素的比值变化后，提出用双对数图解来判别地幔成分、元素总分配系数及母岩浆形成时地幔熔融度的原理。根据Ｌａ，Ｃｅ和Ｓｃ，Ｙｂ在地幔－岩浆过程中地球化学特征，运用上述原理，讨论了峨眉山玄武岩系母岩浆的地幔成分及其变化，计算了地幔矿物相组成和部分熔融度。     

地幔动力学与板块俯冲

通过地幔粘滞性及粘滞结构、地幔热状态、地幔热生成三个方面，探讨了地幔物质发生对流的物理背景，并归纳出地幔对流模式热动力系统，在此基础上剖柏了地幔对流和现代板块构造的直接联系。     

峨眉大火成岩省的岩石地球化学特征及时限

本文根据盐源－丽江岩区和攀西岩区峨眉山玄武岩的地球化学组成，包括各种氧化物之间的关系、微量元素标准化曲线、Th/Yb与Ta/Yb、Ce/Nb与Th/Nb，以及^87Sr/^86Sr与^143Nd/^144Nd值的相互关系，重点对峨眉山玄武岩地幔源的地球化学特点、上扬子地区岩石圈地幔的地球化学特征及成因、地幔热柱与岩石圈地幔的相互作用，以及峨眉山玄武岩的喷发时限进行了初步探讨。     

地幔柱构造理论研究若干问题及研究进展

介绍了目前地幔柱构造理论研究中若干重要问题和最新进展,许多证据显示,地幔柱是严自于核幔边界附近的Ｄ″层发生热扰动并产生地幔柱的热动力源于外地核的不均匀加热作用;一个新启动的地幔柱在穿过整个地幔的缓慢上升过程会形成巨大球状顶冠和狭窄尾柱;地幔柱巨大球状顶冠会导致地壳发生上隆、区域变质作用、地壳深熔作用、构造变形作用和大规模火山作用,形成大陆或大洋溢流玄武岩;地幔柱狭窄尾柱的长期活动会在上覆运动板块上     

地幔不均一性与地幔循环的多维表征和原因思考

地幔早先经核- 幔- 壳分异形成,后受不同尺度对流和循环的影响,因而具有不均一性特征。近三十年来,地幔化学通过研究大洋玄武岩发现了多样地幔端元和非放射性同位素证据并证明了地幔不均一性,逐渐建全了地幔地球化学体系。然而,地幔不均一性如何对应于时空尺度的地幔循环,以及地球演化如何影响地幔不均一性等,仍不清楚。此外,地球物理研究显示,岩石圈厚度差异、中下地幔的波速异常体以及俯冲板片形态的观测为纵横向对流系统提供了空间不均一性证据支持。联合地球化学和地球物理手段对研究地幔不均一性至关重要,用好透视地幔成分与结构的“双目镜”已成为共识。本文从地幔不均一性结合地球化学场、地球物理的不同表现形式,以及现今及历史时期的洋陆格局的对比,多维度联系地幔循环和演化,思考了超大陆旋回与地幔不均一化的内在逻辑。强调了从全球演化角度看地幔不均一性的重要性和提出多手段联合建立地幔循环驱动模型的展望。     

Influence of supercontinents on deep mantle flow

The assembly of supercontinents should impact mantle flow fields significantly, affecting the distribution of subduction, upwelling plumes, lower mantle chemical heterogeneities, and thus plausibly contributing to voluminous volcanism that is often associated with their breakup. Alternative explanations for this volcanism include insulation by the continent and thus elevated subcontinental mantle temperatures. Here we model the thermal and dynamic impact of supercontinents on Earth-like mobile-lid convecting systems. We confirm that insulating supercontinents (over 3000 km extent) can impact mantle temperatures, but show the scale of temperature anomaly is significantly less for systems with strongly temperature-dependent viscosities and mobile continents. Additionally, for continents over 8000 km, mantle temperatures are modulated by the development of small-scale convecting systems under the continent, which arise due to inefficient lateral convection of heat at these scales. We demonstrate a statistically robust association between rising plumes supercontinental interiors for a variety of continental configurations, driven largely by the tendency of subducting slabs to lock onto continental margins. The distribution of slabs also affects the spatial positioning of deep mantle thermochemical anomalies, which demonstrate stable configurations in either the sub-supercontinent or intraoceanic domains. We find externally forced rifting scenarios unable to generate significant melt rates, and thus the ultimate cause of supercontinent breakup related volcanism is probably related to dynamic continental rifting in response to mantle reconfiguration events.     

Apatite in the mantle: implications for metasomatic processes and high heat production in Phanerozoic mantle

The abundance of apatite in Phanerozoic mantle may be greatly underestimated. This study shows that apatite has a widespread occurrence in Phanerozoic lithospheric mantle and can be divided into two geochemically distinct types using halogen content, presence or absence of structural CO₂, Sr and trace element (especially U, Th, and light rare earth) ratios and abundances, and association with either metasomatised mantle wall-rock peridotites (Apatite A) or high-pressure magmatic crystallisation products (Apatite B). Apatite A is inferred to result from metasomatism by CO₂- and H₂O-rich fluids derived from a primitive mantle source region, while Apatite B compositions are consistent with crystallisation from magmas within the carbonate–silicate compositional spectrum.

The presence of significant apatite in the lithospheric mantle is important not only for the geochemical budget but also for assessing heat production and heat flow in the mantle. The measured U and Th contents of mantle apatite average 60 and 200 ppm, respectively and 0.5% apatite would dominate heat production. Metasomatised mantle may also contain amphibole and mica with K₂O and clinopyroxene with detectable U and Th. In lithospheric mantle with a thickness of 70 km, this abundance of apatite would result in mantle heat flow contribution of about 12 mW/m², a significant proportion of the total “normal” mantle heat flow of about 18 mW/m².     

Melt migration and melt-rock reaction in the Alpine-Apennine peridotites:Insights on mantle dynamics in extending lithosphere

The compositional variability of the lithospheric mantle at extensional settings is largely caused by the reactive percolation of uprising melts in the thermal boundary layer and in lithospheric environments.The Alpine-Apennine(A-A)ophiolites are predominantly constituted by mantle peridotites and are widely thought to represent analogs of the oceanic lithosphere formed at ocean/continent transition and slow-to ultraslow-spreading settings.Structural and geochemical studies on the A-A mantle peridotites have revealed that they preserve significant compositional and isotopic heterogeneity at variable scale,reflecting a long-lived multi-stage melt migration,intrusion and melt-rock interaction history,occurred at different lithospheric depths during progressive uplift.The A-A mantle peridotites thus constitute a unique window on mantle dynamics and lithosphere-asthenosphere interactions in very slow spreading environments.In this work,we review field,microstructural and chemical-isotopic evidence on the major stages of melt percolation and melt-rock interaction recorded by the A-A peridotites and discuss their consequences in creating chemical-isotopic heterogeneities at variable scales and enhancing weakening and deformation of the extending mantle.Focus will be on three most important stages:(i)old(pre-Jurassic)pyroxenite emplacement,and the significant isotopic modification induced in the host mantle by pyroxenite-derived melts,(ii)melt-peridotite interactions during Jurassic mantle exhumation,i.e.the open-system reactive porous flow at spinel facies depths causing bulk depletion(origin of reactive harzburgites and dunites),and the shallower melt impregnation which originated plagioclase-rich peridotites and an overall mantle refertilization.We infer that migrating melts largely originated as shallow,variably depleted,melt fractions,and acquired Si-rich composition by reactive dissolution of mantle pyroxenes during upward migration.Such melt-rock reaction processes share significant similarities with those documented in modern oceanic peridotites from slow-to ultraslow-spreading environments and track the progressive exhumation of large mantle sectors at shallow depths in oceanic settings where a thicker thermal boundary layer exists,as a consequence of slow-spreading rate.     

Heterogeneity in the mantle—its creation, evolution and destruction

Small-scale seismic heterogeneity exists at different levels in the lower mantle, and is detected by methods that analyze scattered–not direct–energy from natural and artificial sources. Its vertical distribution, association with subduction, and its ≤ 10-km characteristic scale length strongly suggest that it is chemical/petrological in nature and originally created by melting and differentiation during mid-ocean ridge formation. What is of interest is that the scale lengths of both upper and lower mantle seismic heterogeneity are similar, which supports the view of a common origin explored here. Unlike the lower mantle however, which is broadly homogeneous in structure, the upper mantle contains things that trap and impede the dispersal and re-mixing of heterogeneity: continental crust, lithosphere and cratonic roots. These probably control the depths, the longevity and the age of heterogeneities at shallow mantle levels, and suggest that heterogeneities observed in continental mantle lithosphere are probably old, trapped by the process that grows continental roots. Alternatively, if crustal heterogeneity is controlled by the details of a magmatic process, it must either be somehow continually renewed, for which there is no recognizable surface expression, or it must be depleted over time and the present is a time when, by luck, we may still witness it.     

地幔Sr-Nd-Pb同位素演化的综合模型与n维同位素空间 “地幔面”的地质意义

在n维的Sr-Nd-Pb同位素空间中,几乎所有的大洋中脊玄武岩（MORB）和洋岛玄武岩（OIB）都落在一个虚拟平面上,被称为“地幔面（mantle plane）”。“地幔面”描述了大部分玄武岩的同位素地球化学特征,是最重要的、也是最早提出的地幔动力学演化特征之一,但是长期以来关于“地幔面”的内涵和意义并不清楚。本文通过一个综合模型,反演受岩浆作用控制的地幔微量元素（包括各种同位素母体元素）分异、Sr—Nd—Pb同位素演化,并推导出地幔Sr-Nd-Pb同位素演化的二元参数方程形式。模型表明,通过部分熔融向地壳输出相对富硅、富碱的物质成分,是地幔长期演化的主要特点,这个过程受到两个参数一部分融融程度（F）和岩浆分离的时间（t）-的控制,即n维参数可化为2维,因此在n维同位素空间出现“地幔面”的特征。壳源物资循环,能够使局部地幔偏离“地幔面”,就地幔总体统计特征而言,地壳混染的比例很低,不同的统计数据显示大约1％～6％的系统偏差,即可能的地壳混染程度;进一步模拟,可能作出更加精确的估算。     

攀西裂谷南段鸡街碱性超基性岩微量元素和Sr-Nd 同位素地球化学及其成因探讨

鸡街碱性超基性杂岩体产出于攀西古裂谷南段,地处云南省境内的罗茨地区,空间上与峨嵋山玄武岩紧密伴生。岩体的主体由霞霓钠辉岩、霓霞岩和磷霞岩组成,三类岩石具有相似的微量元素和稀土元素(REE)配分,富集大离子亲石元素K、Rb、Sr、Ba,过渡族元素Sc、Cr和Ni相对亏损,Nb/Ta、Zr/Hf比值在幔源岩的范围内,Sr-Nd同位素沿"幔源趋势"线分布。鸡街碱性超基性岩中不相容元素总体亏损,含量与EMORB相当,稀土总量ΣREE=32.86～70.07偏低,(La/Yb)N=3.03～4.47,HREE亏损,指示源区的适度亏损。微量元素和同位素信息共同指示鸡街碱性超基性岩为地幔岩高压条件下低程度部分熔融的产物(<10%),岩浆演化过程中经历了橄榄石、辉石和少量磁铁矿的结晶分异。霞霓钠辉岩、霓霞岩与磷霞岩来自同一地幔源区,岩浆源区的相对亏损,可能与中-晚二叠纪大量的玄武质岩浆从深部地幔抽取有关。攀西古裂谷的多期次活动为峨嵋地幔柱提供了岩浆通道,地幔柱活动的早期阶段或晚期阶段岩石圈地幔(或混合地幔)低程度部分熔融的碱性岩浆沿此构造薄弱带上侵,形成了攀西古裂谷内呈带状分布的各碱性杂岩体。     

地幔交代作用：研究进展、问题及对策

有关地幔交代作用的研究始于７０年代早期。近２０年来研究工作的贡献是使人们对与地幔演化和不均一性有关的地幔交代作用特征和交代作用机制有了更多的了解，地幔交作用很复杂，它取决于交代作用发生的时间、构造环境、交代介质的种类以及与不同深度地幔内各种地质事件有关的流体的组成。进一步深入开发有关交代作用成因、机制及其与各种地质事件关系的研究，对于深入认识岩石圈地幔的演化和不均一特征具有十分重要的意义。对不同构     

Plume interaction and mantle heterogeneity:A geochemical perspective

Mantle plumes originating from the Core-Mantle Boundary(CMB) or the Mantle Transition Zone(MTZ) play an important role in material transfer through Earth's interior.The hotspot-related plumes originate through different mechanisms and have diverse processes of material transfer.Both the Morganian plumes and large low shear wave velocity provinces(LLSVPs) are derived from the D " layer in the CMB,whereas the Andersonian plumes originate from the upper mantle.All plumes have a plume head at the Moho,although the LLSVPs have an additional plume head at the MTZ.We compare the geochemical characteristics of various plumes in an attempt to evaluate the material exchange between the plumes and mantle layers.The D" layer,the LLSVPs and the Morganian plumes are consisted of subducted slab and post-perovskite from the lower mantle.Bridgmanite would crystallize during the upwelling process of the LLSVPs and the Morganian plumes in the lower mantle,and the residual is a basalt-trachyte suite.Unlike the Morganian plumes,the crystallization in the LLSVPs is insufficient that material accumulates beneath the MTZ to form a plume head.Typically,the secondary plumes above the plume head occur at the edge of the LLSVPs because it is easier for bridgmanite crystal separating from the plume head at the edge,and the residual material with low density upwells to form the secondary plumes.Meanwhile,Na and K are enriched during the long-term crystallization process,and then the basalt-phonolite suite appears in the LLSVPs.The geochemical characteristics of Andersonian plumes suggest that the basalt-rhyolite suite is the major component in the upper mantle.Meanwhile the basalt-rhyolite suite also appears in the LLSVPs and the Morganian plumes because of the assimilation and contamination in the plume head beneath the Mono.     

Refertilization of ancient lithospheric mantle beneath the central North China Craton: Evidence from petrology and geochemistry of peridotite xenoliths

The petrology and geochemistry of peridotite xenoliths in the Cenozoic basalts from Fanshi, the central North China Craton (NCC), provide constraints on the evolution of sub-continental lithospheric mantle. These peridotite xenoliths are mainly spinel-facies lherzolites with minor harzburgites. The lherzolites are characterized by low forsterite contents in olivines (Fo < 91) and light rare earth element (LREE) enrichments in clinopyroxenes. In contrast, the harzburgites are typified by high-Fo olivines (> 91), high-Cr# spinels and clinopyroxenes with low abundances of heavy REE (HREE). These features are similar to those from old refractory lithospheric mantle around the world, and thus interpreted to be relics of old lithospheric mantle. The old lithospheric mantle has been chemically modified by the influx of melts, as evidenced by the Sr–Nd isotopic compositions of clinopyroxenes and relatively lower Fo contents than typical Archean lithospheric mantle (Fo > 92.5). The Sr–Nd isotopic compositions of harzburgites are close to EM1-type mantle, and of the lherzolites are similar to bulk silicate earth. The latter could be the result of recent modification of old harzburgites by asthenospheric melt, which is strengthened by fertile compositions of minerals in the lherzolites. Therefore, the isotopic and chemical heterogeneities of the Fanshi peridotite xenoliths reflect the refertilization of ancient refractory lithospheric mantle by massive addition of asthenospheric melts. This may be an important mechanism for the lithospheric evolution beneath the Central NCC.